Cryogenic type high vacuum pump - UTILISES ABSORPTION PROPERTIES OF ACTIVATED CHARCOAL AND WORKS WITH MODERATE TEMPERATURE

摘要

A cylindrical case (4) has an end plate (3) bolted to the vessel to be evacuated and an opposite end plate (12) bolted to a first stage ion pump (14). It contains a vessel (18) which is filled with liquid nitrogen and covered with activated carbon. Copper tubes (5) connected to the vessel support a series of copper plates (7) which are covered with activated carbon. The plates are held apart by distance pieces (8). The vessel contains a heater (16) which enables the activated carbon to be heated to 300 deg.C to 400 deg.C. Carbon activated at these temperatures has sufficiently good absorption properties to produce vaccua of 10-9 Torr. at a temperature no lower than 77 deg.K. This enables the pump to work with liquid nitrogen rather than liquid helium.